An image sensor creates an image signal by using electrons generated from a photodiode corresponding to an amount of light incident the photodiode through a micro-lens. The electrons generated from the photodiode are output to a data storage unit through a transistor.
In order to manufacture an image sensor, a polysilicon layer serving as a gate of a transistor is formed on a silicon substrate such as a wafer.
After the polysilicon layer is formed, a photoresist pattern having the opening for exposing a part, in which a photodiode is formed later, is formed on the polysilicon layer.
After the photoresist pattern is formed, conductive impurities are implanted into the silicon substrate through the polysilicon layer by using the photoresist pattern as an ion implantation mask, thereby manufacturing the photodiode generating electrons corresponding to an amount of light.
When the photodiode is formed, the conductive impurities are implanted even onto the photoresist pattern.
When the conductive impurities are implanted onto the photoresist pattern, hydrogen ions (H+) are removed from the surface of the photoresist pattern, thereby forming a crust having no hydrogen ions (H+).
The crust formed on the surface of the photoresist pattern is not readily removed through an ashing process.